1. Field of the Invention
An embodiment of the present invention relates to a semiconductor device, a light-emitting device, a power storage device, a driving method thereof, or a manufacturing method thereof.
In this specification, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. For example, a semiconductor element such as a transistor; a power device; an integrated circuit, a power supply circuit, or a power supply converter circuit each including a power device; an electro-optical device; a semiconductor circuit; and an electronic appliance may be included in a category of a semiconductor device or may include a semiconductor device.
2. Description of the Related Art
As a semiconductor device used for a power device, a power device manufactured with the use of silicon is widely prevalent. However, the performance of a power device including silicon is reaching its limit, and it is becoming difficult to achieve higher performance.
In addition, silicon has a narrow band gap and thus there is a limit on the temperature range of operation of power devices using silicon. Thus, in recent years, power devices including SiC or GaN, which has a wide band gap, have been developed.
Patent Documents 1 and 2 disclose the use of an oxide semiconductor for a semiconductor device that is used as a power device for high-power application.